| 词条 | Airspeed Ambassador | ||||||||||||||||
| 释义 |
The Airspeed AS.57 Ambassador is a British twin piston-engined airliner that first flew on 10 July 1947 and served in small numbers through the 1950s and 1960s. The planes are sometimes referred to as "Elizabethans", as they were originally ordered and popularised by British European Airways as the planes used for their "Elizabethan Class" passenger service. Design and developmentThe Ambassador had its origin in 1943 as a requirement identified by the Brabazon Committee for a twin-engined short-to-medium-haul replacement[1] for the Douglas DC-3. Airspeed Ltd. was asked to prepare an unpressurised design in the 14.5-ton gross weight class, using two Bristol Hercules radial engines. In 1943, the company duly set up a dispersed design office in Fairmile Manor at Cobham in Surrey. By the time the British Ministry of Aircraft Production ordered two prototypes from Airspeed, immediately after the end of the Second World War, the design had grown substantially. The Ambassador would be pressurised, have more powerful Bristol Centaurus radials and have a maximum gross weight of almost 24 tons.[1] The revised design offered seating for 47 passengers and, having a tricycle undercarriage, looked more modern than the DC-3s, Curtiss Commandos, Avro Lancastrians and Vickers Vikings that were common on Europe's shorter airline routes. With three low tailfins and a long pointed nose, it shared something of the character of the larger transcontinental Lockheed Constellation. Great efforts were made to reduce drag, to improve performance and cruising efficiency. A NACA laminar-flow wing section was chosen to reduce drag although structural features for wing construction, propeller slipstream over the inner wing and increasing skin roughness with service were some of the things which reduced the optimistic NACA section performance measured in a wind-tunnel. The engine nacelles were first designed with inwardly opening louvres for exhaust gases and cooling air rather than the usual outwardly opening "gills". However, these proved inadequate to cool the engine, so the gills were reinstated. Engine-out climb performance was enhanced by being able to feather the propeller using a zero-torque signal from the engine.[2] Three prototypes were built, the first registered G-AGUA was first flown by George B.S. Errington from Christchurch on 10 July 1947.[3] The second Ambassador, G-AKRD,[4] was used by the Bristol Aeroplane Company from 1953 for flight-testing the Bristol Proteus 705 turbine engine. From March 1958 it was used by Rolls-Royce for test flying the Dart and Tyne turboprops.[1] The third prototype and first Ambassador 2 G-ALFR was used for BEA proving trials[4] and from 1955 in the development trials of the Napier Eland turbine engine. Intensive simulated airline flying, to pave the way for BEA Vanguards, was done in 1958 with two Tyne-powered Ambassadors.[5] Operational historyBritish European Airways (BEA) placed a £3 million order for 20 aircraft in September 1948, and operated them between 1952 and 1958, calling them their "Elizabethan Class" in honour of the newly crowned Queen.[3] The flagship of the fleet was G-ALZN, appropriately named "RMA Elizabethan". The first "Elizabethan" scheduled flight was from Heathrow to Paris Le Bourget on 13 March 1952 and the type later also served the key UK routes. By December 1955 the "Elizabethan Class" had reached 2,230 flying hours annually, per aircraft, the highest in BEA's fleet. However, the last Elizabethan scheduled service for BEA was operated in August 1958, and the type was replaced by the Vickers Viscount. Further sales were not achieved, largely due to the attitude of de Havilland staff at Hatfield following the take-over of Airspeed in 1951. They preferred to use Airspeed's factory at Christchurch to produce military jets designed by de Havilland;[6] the Sales Director was recalled to Hatfield from Australia when Trans-Australia Airlines were on the point of placing an order for 12 Ambassadors.[7] After disposal by BEA, the type helped to establish the scheduled and charter flight operations of Dan-Air, an important airline in the development of package holidays. The type was also used in the UK by Autair and BKS Air Transport. Second-hand Ambassadors were flown for short periods by Butler Air Transport (Australia), Globe Air (Switzerland) and Norrønafly (Norway).[8] The popularity of this aircraft, with its pressurised cabin and good soundproofing, was soon eclipsed by the arrival of turboprop-powered aircraft such as the Vickers Viscount and, some years later, the Lockheed Electra, which featured more reliable engines and faster speeds. The coming of turboprops and the dawning of the Jet Age caused the Ambassador to fall out of favour. Variants
Prototype aircraft with Bristol Centaurus 130 engines, two built.[9]
Production version with Bristol Centaurus 661 engines, 21 built including the production prototype.[10] Projects
Project for either a twin-engined variant with Bristol Proteus or Bristol Theseus engines or a four-engined variant with Napier Naiads or Rolls-Royce Darts.[15] From the first prototypes, the Ambassador's wing had been stressed for four Naiad turboprops, but no four-engined variant flew.[11]
Proposed variant to meet Air Ministry Specification C.13/45 for a medium-range military transport with a rear-fuselage loading ramp.[12] Ten were ordered in October 1946 but were not built, after a review of the design's projected performance produced figures lower than the Air Ministry's requirements.[13]
Proposed military transport variant for the Royal Air Force to meet Air Ministry Specification C.26/43, not built.[12]
Proposed civil freighter variant.[12]
Proposed civil freighter variant.[12] Accidents and incidents
OperatorsCivil operators
Military operators
Aircraft on displayOne Elizabethan, Christopher Marlowe (G-ALZO, c/n 5226), survives and is under long term major restoration by the Duxford Aviation Society at the Imperial War Museum, Duxford near Cambridge.{{cn|date=July 2018}} Specifications{{Aircraft specifications|plane or copter?=plane |jet or prop?=prop |ref={{harvnb|Jackson|1973|p=29}} |crew= three |capacity=Up to 60 passengers |length main= 82 ft 0 in |length alt= 24.99 m |span main= 115 ft 0 in |span alt= 35.05 m |height main= 18 ft 10 in |height alt= 5.74 m |area main= 1,200 ft² |area alt= 111.48 m² |empty weight main= 35,377 lb |empty weight alt= 16,047 kg |loaded weight main= 52,500 lb |loaded weight alt= 23,814 kg |max takeoff weight main= |max takeoff weight alt= |engine (prop)=Bristol Centaurus 661 |type of prop= two-row sleeve-valve radial piston engine |number of props=2 |power main= 2,625 hp |power alt= 1,958 kw |max speed main= (75% power, 11,650 (5,284 kg)) 312 mph |cruise speed main= 260 mph |cruise speed alt= 418 km/h |range main= 550 miles |range alt= 885km |ceiling main= |ceiling alt= |climb rate main= 1,250 ft/min |climb rate alt=6.35 m/s |loading main= |loading alt= |power/mass main= |power/mass alt= }} See also{{Aircontent|related= |similar aircraft=
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|see also= }} References
1. ^1 2 Phipp 2007, pp. 75-77. 2. ^Boot, pp.25-26. 3. ^1 Singfield 2000, p. 12. 4. ^1 Jackson 1973, p. 30. 5. ^Rolls-Royce Aero Engines, Bill Gunston 1989, Patrick Stephens Limited, {{ISBN|1-85260-037-3}}, p.128 6. ^Masefield and Gunston, p.83 7. ^Masefield and Gunston, p.214 8. ^Jackson 1973, pp. 395–396. 9. ^Jackson 1973, p. 25. 10. ^Jackson 1973, p. 26. 11. ^Boot, p.25 12. ^1 2 3 4 "Airspeed Type Designations." Flight International, 23 February 1951, p. 228. 13. ^Boot, p.24 14. ^1 Eastwood and Roach 1991, p. 7. 15. ^"Accident description: Airspeed AS.57 Ambassador 2, 8 April 1955." Aviation-safety.net. Retrieved: 13 November 2010. 16. ^Eastwood and Roach 1991, p.12. 17. ^"Accident description: Airspeed AS.57 Ambassador 2, 6 February 1958." Aviation-safety.net. Retrieved: 6 May 2012. 18. ^https://aviation-safety.net/database/record.php?id=19660414-1 19. ^https://aviation-safety.net/database/record.php?id=19670914-0 20. ^"Accident description: Airspeed AS.57 Ambassador 2, 3 July 1968." Aviation-safety.net. Retrieved: 6 May 2012. 21. ^"Accident description: Airspeed AS.57 Ambassador 2, 30 September 1968."Aviation-safety.net. Retrieved: 13 November 2010.
External links{{commons category|Airspeed AS.57 Ambassador}}
5 : Airspeed aircraft|British airliners 1940–1949|Aircraft first flown in 1947|High-wing aircraft|Twin piston-engined tractor aircraft |
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